Few stories begin with a cell plucked from the mammary gland of a ewe, go on to shower worldwide acclaim on a team of British scientists and then degenerate into a squabble over who deserves the credit. But then there's nothing ordinary about the tale of Dolly the sheep.

Born on July 5 1996, Dolly propelled Britain to the vanguard of cloning science. For the first time, a sheep had been created from a hollowed-out egg fused with a cell from an adult animal. The provenance of the cell led researchers to name the lamb with a nod to the country singer Dolly Parton.

Dolly brought fame and admiration for Professor Ian Wilmut, the head of the research group at the Roslin Institute in Edinburgh. When the seminal paper describing the work was published in the journal Nature in 1997, he entered the rarefied territory of scientist as household name. Researchers around the world clamoured for details of the group's techniques, eager to repeat the feat.

The boost that Dolly gave British science was incalculable, but the story is not one of collegiate collaboration crowned by shared glory. This week, Prof Wilmut admitted to an employment tribunal in Edinburgh that his involvement was less than may have been portrayed. When asked by a lawyer whether the statement "I did not create Dolly" was accurate, he replied "Yes." The tribunal is hearing a claim from Prim Singh, a biologist, that Prof Wilmut harassed him. The tribunal continues.

The admission from Prof Wilmut raises the question: who did clone Dolly? In the hearing, the scientist said that while he did not develop the technology or conduct the experiments, he instructed the team on the nuclear transfer techniques and coordinated the project. In further evidence, he said Prof Keith Campbell, an expert on the biology of cell cycles, deserved 66% of the credit for Dolly.

The comments have stirred up deep resentments. Some scientists, who spoke to the Guardian under condition of anonymity, believe the group would still be trying to clone an animal were it not for Prof Campbell, who worked out that each egg and cell used in a cloning attempt had to be carefully coordinated for the embryo to have any chance of surviving.

It is understood that Prof Wilmut's handling of the Dolly affair was a factor behind Prof Campbell's decision to quit the institute in 1997 and transfer his skills to another Edinburgh-based research firm.

But the debate does not end there. One member of the Dolly team, a technician called Bill Ritchie, along with Karen Mycock, another technician, was responsible for the intricate and arduous egg and cell manipulation needed to create each clone. At the end of each day, the few successfully cloned embryos were collected and transplanted into ewes. "There were two people doing nuclear transfer that day and it could have been either who created the embryo that made Dolly," said one scientist close to the project.

Mr Ritchie argues that his and Ms Mycock's names should have appeared on the list of authors of the 1997 research paper. Instead, the technicians both appear in the small print of acknowledgements at the end of the report's list of references.

The row reveals aspects of the scientific process that will not surprise anyone working in the field. Modern science invariably requires large teams and with the hierarchy come politics. As one scientist put it: "It's one of those scenarios. You have a hierarchy of employment and you need the job. They dictate the rest."

Many scientists say technicians are merely doing what they are told, while the credit - the all-important name on the paper - goes to those whose intellectual thought made the research a success. "You get some papers where the authors haven't done a scrap of work themselves, it's all down to the technicians acknowledged at the back," said one researcher.

Mr Ritchie believes that while Prof Campbell's contribution was crucial for the Dolly project to succeed, the lab work conducted by himself and Ms Mycock was never properly credited. According to Mr Ritchie, Dolly was only born after the two of them put in weeks of labour-intensive lab work. In all, 430 eggs were surgically removed from ewes and given to the technicians. Each one had to have its DNA removed, essentially hollowing out the eggs with a sharpened glass capillary.

Each empty egg was then filled with an adult cell taken from a sheep and zapped with an electric current to fuse the two. Of the original 430, only 270 eggs were successfully hollowed out and fused with other cells and only 29 of those grew into small balls of cells known as blastocysts, the precursors of embryos. Of these, only one that was implanted developed successfully, dividing and growing inside a surrogate female until, five months later, Dolly was born.

According to Mr Ritchie, the technicians did most of the work that led to Dolly, but they got none of the praise. "He [Wilmut] is saying he did a third and Keith did two-thirds. But I don't think I appear in there at all, to be honest" he said.

Scientists contacted by the Guardian said the question of credit is frequently a divisive one. "It can be extremely difficult. The whole cloning process involves a lot of people. It all comes down to how far down the list you want to go," said one.

Earlier this year, Prof Miodrag Stojkovic, who created Britain's first cloned human embryo while working at Newcastle University, admitted that a disagreement with Prof Alison Murdoch, his colleague at the Newcastle Fertility Centre, had been a significant factor in his leaving to take up a post in Spain. He objected to Prof Murdoch announcing the work at a press conference and accused her of taking credit for his team's research work. Newcastle University insists Prof Murdoch's contribution was important.

Prof Wilmut, now at Edinburgh University, heads only the second group in Britain to be granted a licence to clone human embryos by the Human Fertilisation and Embryolgy Authority. Dolly was put down by veterinarians in February 2003 at the age of six after she developed premature progressive lung disease.